It is well known to use springs in force devices as shown in the following U.S. Pat. Nos.: 730,477; 836,752; 948,140; 1,359,449; 1,574,491; 2,007,880; 2,174,356; 2,199,553; 3,116,634; 3,175,393; 3,942,367.
It is also known to use a band to transmit a force from a rotating member to a coil spring as seen in U.S. Pat. Nos. 836,752, 948,140, 3,116,634, 3,942,367 and 3,175,393. The latter patent discloses the use of bands around rotatable discs with coil springs secured to the free ends of the bands in a dynamometer.
U.S. Pat. Nos. 1,574,491, 2,007,880, 2,174,356 and 2,199,553 and further illustrative of torque testing devices employing coil springs.
Applicant's invention overcomes the problems of the prior art of the employment of pretensioned extension springs positioned in parallel and involving negligible friction and provided with a simply operated slider means for preloading the springs and zero adjusting the accompanying pointer. The gram gauge of the invention is compact, accurate and inexpensive as compared to prior art gram gauges.